1. Technical Field
The present invention generally relates to the field of multi-touch technology and, particularly, to a method for detecting multiple touch positions on a touch panel.
2. Description of the Related Art
Touch panels have the advantages of small size, low cost, low power consumption and long life-span, and thus are widely applied on various electronic products as input devices. The user only is required to move or touch an object (e.g., an electrically conductive object such as the user's finger, a stylus or the like) on a touch panel to control a cursor on a window in relative movement or absolute coordinate movement, so that various inputs including text written, window scroll and key press simulation can be performed.
Depending on the type of object used and the manner of touch position is determined, touch panels are generally classifiable as capacitive-type, resistive-type, electromagnetic (EM)-type, surface acoustic wave (SAW)-type and infrared-type touch panels. The capacitive-type touch panel is an input device allowing a user's finger to move on a smooth panel so as to control the movement of the cursor, when the user's finger touches the panel, magnitudes of sensed energy on a first dimensional direction and a second dimensional direction of the touch position are caused to be changed, so that a sensing element can detect whether the capacitive-type touch panel is touched or not according to the magnitudes of sensed energy. Owing to its thin profile, the capacitive-type touch panel is suitably integrated into an ultra-thin notebook, keyboard, digital player or other device. Furthermore, since its non-mechanical design, the capacitive-type touch panel is more easily maintained.
Referring to FIG. 5, a conventional method for detecting multiple (e.g., two) touch positions on a capacitive-type touch panel is difficult to correctly detect the coordinates (A, A), (C, C) of actual touch positions and only can detect a region containing four coordinates (A, A), (C, A), (C, C) and (A, C) is touched. However, the coordinates (C, A) and (A, C) are virtual touch positions (i.e., actually are not touched) rather than the actual touch positions. Therefore, since the accuracy of detect result is limited, may result in the inconvenience of the user and significantly hinder the wide application of the capacitive-type touch panel.